1. Field of the Invention
The invention relates to a system for the sealing of roofs comprising a first sealing layer that is mechanically attached to a support to be protected, and a second self-adhesive sealing layer that is attached to the first sealing layer. It also relates to the constituents of that first sealing layer.
2. Brief Description of the Background of the Invention Including Prior Art
Various systems have been proposed for the sealing of roofs. The most frequently used system among them consists of applying a bituminous or asphalt coating in two layers, where the first layer is mechanically fixed to the support to be protected, whereas the second layer is welded with a welding torch onto the first layer. However, such a system is not always convenient since torch welding requires very specialized manpower and comprises certain obvious risks, since the support to be protected is flammable.
Moreover, the mechanical attaching of the first layer brings about the risk of perforation of the assembly by the screws or the rivets following the settling of the support and/or the movements of the structure.
Another sealing system consists in applying a self-adhesive sealing sheet directly onto the support to be protected, where the upper surface of the sealing sheet is protected by a film of a synthetic material. The jointing of the adjacent sheets is achieved either by partial overlapping or by applying of a complementary strip covering both edges of the two sheets.
However, the application of this type of self-adhesive material requires that the placement surface be even, clean, and without roughnesses and dust. It is therefore difficult to use this system on irregular supports such as thermal insulating materials or over old sealing coverings, for example, in the case of a sealing restoration or overhauling.
On the other hand, due to the total adherence, their sheets have to tolerate the movements of the support and therefore risk being rapidly damaged.
Furthermore, in case of the building-up of gas or water vapor between the support and the waterproof sheet due to a migration of humidity, there is brought about the risk that excessive pressure zones are created by these gases and that bubbles and swellings occur which can lead to the rupturing of the sealing sheet.
Finally, in very windy or breezy regions it is not always possible to obtain a sufficient adhesion of the self-adhesive sheet to its support.